1. Technical Field
The present disclosure is directed to a device for determining a circumference of a cavity such as a spinal disc cavity post nucleotomy. More particularly, the present disclosure is directed to a device for determining whether the cavity is dimensionally sufficient to receive a prosthetic implant.
2. Description of the Related Art
Applications are known in the art which create interior disposed cavities of unknown dimensions associated with herniated discs. A device for determining parameters of blind voids is described in the art. See, e.g., U.S. Pat. No. 6,500,132 B1 to Li (hereinafter “Li”).
Although potentially useful, the Li device is deficient. For example, as described therein, the device includes a first flexible element that bulges outwardly to engage interior walls of the void. The device includes a second element that bulges outwardly in a configuration substantially duplicative of the first element bulge, the second element being outside of the void and subject to observation. Although, it may be possible for a surgeon to observe the second flexible element outside the void, the surgeon may also desire to use radiologic imaging to observe the device within the void. However, such imaging using Li's device may be negatively affected by the presence of other elements, e.g., actuator, engagement member, and/or plates, in addition to the first flexible element which obscure the image, i.e., the surgeon may have difficulty distinguishing between the flexible element, the plates, the actuator and the engagement member in determining the size of the blind void.
Additionally, Li's device has a relatively large profile, and a thick width which may prove cumbersome More importantly, the second flexible element would not function within the confines of a narrow cannula since it would be unable to bulge against the side walls of the cannula. If a nucleotomy is being conducted using, inter alia, a cannula, the surgeon would have to remove the cannula before introducing Li's device. The cannula would then be reintroduced for additional spinal procedures, which is inefficient.
Further, depending on the size of the disc space, one or more differently sized prosthetic implants can be introduced into the void during surgery once the void size is determined. Li's device is not well-suited for precisely determining the size the blind void for a pre-dimensioned prosthetic implant in an efficient manner. When using Li's device, the surgeon may visually observe the second flexible element's size. However, to precisely determine the size of the void for the prosthetic implant, the surgeon must measure the second flexible element and then match that measurement to a size of the prosthetic implant. The process may take extra time and requires multiple measurements. It would be advantageous for the surgeon to simply use the device and then automatically know the correct prosthetic implant size.
There is a need in the art for a device for quickly and efficiently determining whether the amount of the nucleus pulposus removed from the intervertebral disc space is sufficient to create a cavity to accommodate a predetermined spinal nucleus implant. Furthermore, there is a need for a device for measuring a cavity that is compact, and has a substantially narrow profile to be quickly introduced into the cavity for measurement through a cannula and then quickly removed from the cannula. There is also a need in the art for a device for measuring a cavity that can be used with imaging techniques and x-ray machines or other scanning devices without cumbersome elements that may obscure the view. There is also a need in the art for a device for measuring the circumferential dimension of a cavity that automatically indicates to the practitioner whether the circumferential dimension is sufficient to accommodate a predetermined implant size. Thereafter, the surgeon can quickly withdraw the instrument through a cannula.